Printed Frequency Beam-Scanning Antenna With Flat Gain and Low Sidelobe Levels

A frequency beam-scanning antenna with backfire-to-endfire beam-steering capability is proposed and investigated. This antenna is with printed planar structure that consists of a low-loss slow-wave printed meander line based on the even-mode bilateral broadside-coupled suspended microstrip line (BSML). The propagation properties of the meander-line unit and its principles for frequency-scanning applications are studied extensively. This printed antenna achieves the measured beam scanning of ${-}$ 27.5 $^{\circ}$ to 46 $^{\circ}$ with the frequency sensitivity of 43.24 $^{\circ}$ /GHz and a maximum gain of 15.5 dBi. The antenna exhibits flat gain of more than 13 dBi in the whole frequency range from 8.9 to 10.6 GHz. The sidelobe levels are near 20 dB. The design flexibility of this kind of antenna is shown.